Evidence against dopamine D1/D2 receptor heteromers

• Published in: Molecular psychiatry Vol. 20; no. 11; pp. 1373 - 1385
• Main Authors: Frederick, A L, Yano, H, Trifilieff, P, Vishwasrao, H D, Biezonski, D, Mészáros, J, Urizar, E, Sibley, D R, Kellendonk, C, Sonntag, K C, Graham, D L, Colbran, R J, Stanwood, G D, Javitch, J A
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2015; Nature Publishing Group
• Subjects: 13/51; 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine - analogs & derivatives; 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine - pharmacology; 42/44; 631/378; 64/60; 9/10; 96/33; Animals; Behavioral Sciences; Biological Psychology; Bioluminescence; Biosensors; Brain slice preparation; Corpus Striatum - drug effects; Corpus Striatum - metabolism; Depression, Mental; Dopamine; Dopamine Agonists - pharmacology; Dopamine Antagonists - pharmacology; Dopamine D1 receptors; Dopamine D2 receptors; Dopamine receptors; Drug therapy; G protein-coupled receptors; Grooming; Grooming - drug effects; GTP-Binding Protein alpha Subunits, Gq-G11 - genetics; GTP-Binding Protein alpha Subunits, Gq-G11 - metabolism; HEK293 Cells; Humans; Kinases; Life Sciences; Ligands; Localization; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Male; Medicine; Medicine & Public Health; Mental disorders; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Molecular; Motor Activity - drug effects; Motor Activity - genetics; Mutants; Neurosciences; Nucleus accumbens; Nucleus Accumbens - drug effects; Nucleus Accumbens - metabolism; Oligomers; original-article; Pharmacology; Pharmacotherapy; Phospholipase C; Phosphorylation - drug effects; Physiological aspects; Protein Multimerization - drug effects; Protein Multimerization - physiology; Protein Structure, Tertiary; Proteins; Psychiatry; Receptor mechanisms; Receptors, Dopamine D1 - genetics; Receptors, Dopamine D1 - metabolism; Receptors, Dopamine D2 - genetics; Receptors, Dopamine D2 - metabolism; Risk factors; Schizophrenia; Signal transduction; United States; New York; United States > US; Nashville Tennessee
• ISSN: 1359-4184; 1476-5578; 1476-5578
• DOI: 10.1038/mp.2014.166

Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation, because their purported potential to manifest signaling and pharmacological properties that differ from the component receptors makes them highly attractive for the development of more selective pharmacological treatments. In particular, dopamine D1 and D2 receptors have been proposed to form hetero-oligomers that couple to G αq proteins, and SKF83959 has been proposed to act as a biased agonist that selectively engages these receptor complexes to activate G αq and thus phospholipase C. D1/D2 heteromers have been proposed as relevant to the pathophysiology and treatment of depression and schizophrenia. We used in vitro bioluminescence resonance energy transfer, ex vivo analyses of receptor localization and proximity in brain slices, and behavioral assays in mice to characterize signaling from these putative dimers/oligomers. We were unable to detect G αq or G α11 protein coupling to homomers or heteromers of D1 or D2 receptors using a variety of biosensors. SKF83959-induced locomotor and grooming behaviors were eliminated in D1 receptor knockout (KO) mice, verifying a key role for D1-like receptor activation. In contrast, SKF83959-induced motor responses were intact in D2 receptor and G αq KO mice, as well as in knock-in mice expressing a mutant Ala 286 -CaMKIIα that cannot autophosphorylate to become active. Moreover, we found that, in the shell of the nucleus accumbens, even in neurons in which D1 and D2 receptor promoters are both active, the receptor proteins are segregated and do not form complexes. These data are not compatible with SKF83959 signaling through G αq or through a D1/D2 heteromer and challenge the existence of such a signaling complex in the adult animals that we used for our studies.